Effectiveness of Wastewater Treatment Plants in Reducing Pathogens in the Paso del Norte Region Geoffrey B. Smith New Mexico State University, Las Cruces, NM Kevin H. Oshima Environmental Protection Agency, Cincinnati,OH

Project Objectives Based on high incidence of pathogen occurrence in Rio Grande and irrigation canals (eg., Morales et al. 2006), effectiveness of local wastewater treatment plants was questioned. Recently developed methods (Morales et al. 2003) allow for quantification of protozoa, bacteria and virus.

Paso del Norte Study Location

Methods One liter sampled from Influent, Ten liters of Effluent sampled. Protozoa. Giardia and Cryptosporidium quantified by EPA Method 1623, with a Immunomagnetic Separation (IMS) purification step. Bacteria. Helicobacter pylori. Quantified by selective medium containing 5 antibiotics and 2 antifungal agents (Morales and Vidal). Fecal coliforms by Standard Method 9222 D. Virus. E. coli phage and Pseudomonas phage by EPA method 1602.

Influent Protozoa El Paso del Norte

Cryptosporidium - El Paso del Norte Sewage Pathogens as Epidemiology Assay

Sewage Pathogens as Indicators of Current Disease? Cryptosporidium

Cryptosporidium Occurrence is Correlated between Las Cruces, NM and El Paso,TX

Cryptosporidium Occurrence is Correlated between El Paso,TX and Juarez, MX

No Relationship between Fecal Coliforms and Coliphage Virus in Wastewater

Log Reductions: How well does a treatment plant reduce the levels of pathogens? Eg. InfluentEffluentLog Reduction Plant A10,00010log(10,000/10) = 3 (one-thousand-fold lower) Eliminated 99.9% of influent Plant B10, log(10,000/1000) = 1 (ten-fold lower) Eliminated only 90% of influent

Protozoa Log Reductions – El Paso, TX

Protozoa Log Reductions - LasCruces,NM

Protozoa Log Reduction - Juarez, MX

Fecal Coliform – Log Reductions

Conclusions Las Cruces, NM and El Paso, TX wastewater treatment plants functioned properly over the 2-year study. The Ciudad Juarez Planta Norte functioned in reducing putative Helicobacter pylori, but had little or no effect on fecal coliforms, and coliphages. On average, protozoa were reduced by 1 log (90% reduction).

Giardia - El Paso del Norte.

Giardia (Influent) Similar trends in Las Cruces and El Paso